In recent years, natural language processing apparatuses have been developed in which a device incorporating a computer recognizes a natural language uttered by a human, and which automatically perform processing or provide a response based on the recognized content. For example, a natural language processing apparatus is being studied and developed which makes it possible for a humanoid robot to hold a “conversation” with humans. The humanoid robot is provided with a conversation system including a speech input unit such as a microphone; a speech recognition unit which recognizes a natural language sentence from an input speech; and a speech output unit which generates and outputs a response to the recognized natural language sentence.
Patent Document 1 describes an example of a language generating apparatus for processing natural language sentence. In the language generating apparatus of Patent Document 1, when a response sentence with respect to a certain problem is generated, a language expression sequence for describing the content of an action for solving the problem is generated at the point in time of finalization of the content.